In the typical fuel vapor vent valve for a motor vehicle fuel tank wherein the valve is adapted to prevent spillage in case of shaking, tilting or rollover of the vehicle, the valve normally opens the fuel tank to an orifice that is connected by a vapor exit passage in the valve body to a vapor hose leading to a fuel vapor storage device. The valve body is commonly made as a one-piece plastic injected molded part that for simplicity of design has a simple direct connection between the orifice and the vapor exit passage. However, this connection has a tendency to collect and pass any liquid fuel issuing from the orifice under pressure from the tank on to the vapor storage canister. The latter contains a fuel vapor absorber such as carbon and any liquid fuel delivered thereto will quickly reduce its vapor adsorbing ability. It is difficult to configure the top of the molded body with a vapor exit passage connection that would somehow trap this liquid after it passes through the orifice and then drain the trapped liquid back to the tank. This is also the case where the valve is omitted and only venting is provided through an orifice in a vent body that mounts on the fuel tank.
As to any such possible fuel drainage back to the tank in the case of a vent assembly having a valve that is adapted to block the orifice on overfill, vehicle shaking, tilting and/or vehicle rollover, there is also the consideration of adversely affecting the operation of the valve as it is required to provide for normal venting operation in an upright position but close under these various circumstances to block exit of fuel from the tank. Any such drainage path for liquid fuel trapped downstream of the orifice can not provide a possible path for fuel vapor to vent around the valve in the normal upright attitude of the tank or allow liquid fuel to escape from the tank when tipped or inverted. An example of such systems is set-forth in U.S. Pat. No. 5,044,389, assigned to the assignee of the present invention.
One solution to such problems is set-forth in U.S. Pat. No. 5,413,137, also assigned to the assignee of the present invention. The fuel vapor vent assembly set-forth in the '137 patent embodies a fuel impervious insert that is adapted to be mounted in such a vent or vent valve body and defines both a vertically oriented vent orifice and a liquid basin extending about the exit of this orifice. A simple cavity formed in the interior of the top of the plastic body co-operates with the basin in the insert to define an expansive chamber elevated above the orifice and this chamber communicates the orifice with a horizontal vapor exit passage in the plastic body adapted to be connected to a vapor storage device. The expansive chamber forms an elevated liquid trap at the exit of the orifice that traps liquid from the venting fuel vapor while permitting venting to continue therethrough and then drains the trapped liquid in the basin back into the tank through the orifice in the insert when the pressure in the fuel tank is relieved. The liquid trapping chamber has a ceiling directly opposite the orifice dead ending the vapor stream issuing therefrom and the vapor exit passage is connected to the expansive chamber at a point above the basin. These features combine to aid in separating any liquid fuel out from the vapor and down into the basin and prevent it from passing on to the vapor exit passage and thence to the vapor storage canister.
While suitable for their intended purpose, the fuel vapor vent assemblies set-forth in the aforesaid prior art patents do not include provision for venting vapor from the tank as the float is closing at the same rate at which the fuel tank is being filled nor do they provide a predetermined vapor dome space within said tank to accommodate vapor pressure increases when the refueling valve is closed. Further, the unitary body arrangement is configured to locate the valve seat close to the tank top and vent openings are located at the base of the unitary body such that they will be immersed in fuel when the tank level reaches the float so that venting will be restricted as the float moves between its normally open position and its normally closed position.
Another fuel vapor vent valve that obviates the aforesaid problem is setforth in U.S. Pat. No. 5,687,756 also assigned to the assignee of the present invention. The valve shown in the '756 patent provides a fuel vapor vent device that will vent vapor during fuel fill at the same rate as the rate of fuel flow into the tank while preventing liquid fuel flow to a fuel vapor storage canister. Such operation is in part provided by a valve body having a vapor exit passage and a liquid inlet passage and the body is connected to the top of a fuel tank in depending relationship therewith and the valve includes a float and a valving element carried by the float and tiltable with respect to the float for compensating for tilt and further characterized by the body further including a vapor exit port adjacent the top and also including a vent tube with a valve seat located below the vapor exit port for preventing liquid fuel particles from entering the vapor exit passage. The vent tube has a length more than one half of that of said body for locating said valve seat at a distance from the upper wall of the fuel tank that will provide for a predetermined vapor dome space within said tank to accommodate vapor pressure increases when the refueling valve is closed. While suitable for its intended purpose, the length of the vent tube is not always suitable for applications in different fuel tank configurations and requires assembly and the valve seat thereon is not isolated from fuel to so as to minimize fuel carryover to a charcoal canister resulting from violent dynamics of fuel in a closed vessel in response to vehicle maneuvers.
Accordingly, an object of the present invention is to provide a fuel vapor control valve configured to be connected vertically within the upper space of a fuel tank and including connections to a charcoal canister and further including a valve body having a float therein with a valve having a sealing surface isolated from fuel and engaging and sealing against a valve seat for preventing fuel flow through a vapor vent port from the valve body and the valve body having an opening configured to direct fuel vapors from the fuel tank to the interior of the valve body the fuel vapor control valve being characterized by a baffle connected to the interior of the valve body separating the valve body into a vapor space and a fuel space and a connecting rod connected to the float and raised therefrom a predetermined distance to isolate a valve element sealing surface from fuel and directed generally vertically through the baffle and a valve element located on the connecting rod within the vapor space and wherein the baffle and connecting rod are configured such that fuel entry into the vapor space will be delayed until the float is displaced by the entry of fuel into the valve body to cause the valve element to seal the valve seat to prevent fuel passage through the vapor vent port during violent vehicle maneuvers.
A further object is to provide such a fuel vapor control valve of wherein the baffle divides the valve body to form an upper chamber and a lower chamber; the fuel inlet openings into the valve body communicating only with said lower chamber and vapor exit openings being formed within the valve body to communicate the vapor dome of a fuel tank with the upper chamber and wherein a skirt on the valve body cover is configured for encompassing the valve seat and the valve element when it is both opened and closed; the valve body having fuel vapor openings therein located outboard of the skirt at a position shielded by the skirt such that the skirt deflects fuel droplets directed through the fuel vapor openings from entering the vapor vent port.
Still another object of the invention is to provide such a fuel vapor control valve having a body dividing baffle therein including a hole for guiding the valve sealing surface isolating connecting rod within the body and for permitting movement of the connecting rod with respect to the baffle.
One feature of the invention is to provide the baffle in the aforesaid vapor control valve as an inverted cone baffle connected to the valve body and including a hole for passage of the valve sealing surface isolating connecting rod there through during closure of the vent valve and the inverted cone baffle operative to deflect fuel particles in the lower chamber from passing through the vapor vent port when said vent valve is open.
Another feature of the invention is to provide the baffle formed as a planar divider wall connected to and directed transversly across the valve body and including a hole for guiding the connecting rod there through during closure of the vent valve and the planar divider wall operatively deflecting fuel in the lower chamber of a valve body from passing through the vapor vent port.
Yet another object of the invention is to provide universal connections between the valve sealing surface isolating connecting rod, the float and the valve element for adjusting the position of the valve element during closure against the valve seat in response to fuel slosh produced by any normal to violent vehicle maneuvers.
A further object is to provide such connections as a first ball joint on the upper end of the float connected to a socket on one end of the connecting rod and the connecting rod including a second ball joint connected to a ball socket on a valve carrier and including a valve element on the valve carrier located by the upper and lower connections to seal a valve seat for preventing vapor escape when the float is raised within the valve body by displacement of liquid flowing into the valve body through the inlets therein.
These and other objects, advantages and features of the present invention will become more apparent from the following description and accompanying drawings wherein: